Red Sox righthanded reliever Bobby Jenks underwent back surgery at Massachusetts General Hospital yesterday.
Jenks was injured in June but the surgery was delayed until medication cleared up a pulmonary embolism that was found while treating the back injury.
The surgery was on the left side of his back and is not expected to affect how Jenks throws.
General manager Ben Cherington said last week that Jenks should be able to pitch at some point in spring training.
Jenks was a huge disappointment last season, appearing in only 19 games after signing a two-year, $12 million deal. He had a 6.32 ERA.